Melissa C. Smith

Host range validation, molecular identification and release and establishment of a Chinese biotype of the Asian leaf beetle Lilioceris cheni (Coleoptera: Chrysomelidae: Criocerinae) for control of Dioscorea bulbifera L. in the southern United States

Abstract Dioscorea bulbifera, an Asian vine, is invasive in the southeastern USA. It rarely flowers but propagates from potato-like bulbils formed in leaf axils, which persist into the subsequent growing season. Lilioceris cheni Gressitt and Kimoto, a foliage-feeding beetle (Coleoptera: Chrysomelidae: Criocerinae) from Nepal, had been tested, proven to be a specialist and approved for release as a biological control agent. Regulatory delays, however, resulted in the demise of quarantine-held colonies, and acquisition of new Nepalese stock proved untenable. Searches then undertaken in southern China resulted in the collection of over 300 similar beetles. Two Chinese Lilioceris species were identified: one confirmed to be L. cheni and the other identified as Lilioceris egena (Weise). Mitochondrial analysis revealed an exact DNA match between some Chinese and one of the two Nepalese c oxidase subunit I haplotypes and all Chinese L. cheni haplotypes clustered as a single species but the comingling of the two species aroused concerns over possible hybridisation. These concerns were allayed by nuclear D2 analysis showing the absence of dual parental sequences. Nonetheless, diligence was exercised to ensure that the Chinese strains were safe to release. Abridged host testing using critical test species verified specificity. Caged releases during autumn 2011 documented the ability of adult beetles to overwinter in south Florida despite a prolonged lack of foliage. Open releases the following year produced vigorous populations that caused extensive defoliation. Preliminary observations indicate that L. cheni now contributes to the control of D. bulbifera and the bulbil-feeding L. egena should complement these effects if its host range proves appropriate.

Dispersal and establishment of new populations of the biological control agent Floracarus perrepae (Acariformes: Eriophyidae) on Old World climbing fern, Lygodium microphyllum (Polypodiales: Lygodiaceae).

Summary The mite Floracarus perrepae Knihinicki & Boczek (Acariformes: Eriophyidae), a biological control agent of Lygodium microphyllum (Cav.) R. Br (Polypodiales: Lygodiaceae), Old World climbing fern, was released in south Florida from 2008 to 2010 but did not readily establish in the field. The original release sites were re surveyed in 2013 and the mite has established within Jonathan Dickinson State Park and has dispersed to L. microphyllum patches outside the park at a rate of 3.5 ± 0.6 km/yr. The mite has also dispersed to the Cape Sable region of Everglades National Park.

Current status of the biological control agent Neomusotima conspurcatalis (Lepidoptera: Crambidae), on Lygodium microphyllum (Polypodiales: Lygodiaceae) in Florida.

Summary The brown Lygodium defoliating moth, Neomusotima conspurcatalis Warren (Lepidoptera: Crambidae), was released beginning in 2008 to control Old World climbing fern, Lygodium microphyllum (Cav.) R. Br (Polypodiales: Lygodiaceae). The moth readily established in Jonathan Dickinson State Park, but at other sites populations remained at low densities or were locally extirpated. In 2012 and 2013, we recovered N. conspurcatalis populations at all original release sites except Everglades National Park and those treated with herbicide. The original releases of 4,000 or more individuals per site were entirely successful, pointing to a strategy that focuses on numbers at this target level or beyond for future releases in Florida.

First report of an egg parasitoid reared from Neomusotima conspurcatalis (Lepidoptera: Crambidae), a biological control agent of Lygodium microphyllum (Schizaeales: Lygodiaceae)

Neomusotima conspurcatalis Warren (Lepidoptera: Crambidae) was first released in Florida, USA, as a biological control agent of Lygodium microphyllum (Cavanilles) R. Brown (Schizaeales: Lygodiaceae), Old World climbing fern, in 2008. The first egg parasitoid, a Trichogramma sp. (Hymenoptera: Trichogrammatidae), was reared from N. conspurcatalis in 2013. The parasitoid is widely distributed in south Florida, where its egg mass parasitism rates can reach 100%. Sumario Neomusotima conspurcatalis Warren (Lepidoptera: Crambidae) fue liberado por primera vez en la Florida, EE.UU., como un agente de control biologico de Lygodium microphyllum (Cavanilles) R. Brown (Polypodiales: Lygodiaceae), el helecho trepador del Viejo Mundo, en 2008. El primer parasitoide de huevos, un Trichogramma sp., fue criadocriado de N. conspurcatalis en 2013. El parasitoide se distribuye ampliamente en el sur de Florida, donde sus tasas de parasitismo de masas de huevos pueden llegar al 100%. View this article in BioOne

Oviposition choice and larval performance of Neomusotima conspurcatalis on leaflet types of the invasive fern, Lygodium microphyllum

Lygodium microphyllum (Cavanilles) R Brown (Lygodiaceae), Old World climbing fern, invades wildlands in central and southern Florida, USA, and causes considerable habitat disturbance. Efforts to develop an effective biological control strategy have focused on several folivorous insects and a leaf‐galling mite from southeast Asia and Australia. Neomusotima conspurcatalis Warren (Lepidoptera: Crambidae) is a foliage‐feeding moth that specializes on Lygodium species. First released in 2008, N. conspurcatalis successfully established in Florida and is dispersing throughout the L. microphyllum‐invaded range. We investigated whether N. conspurcatalis display any preference (oviposition or larval feeding) between two leaflet morphologies, i.e., fertile spore‐producing vs. sterile leaflets. Furthermore, we examined whether oviposition and no‐choice diets on either fern leaflet type conferred any possible selective advantages (e.g., weight, emergence success) to the offspring. Finally, we analyzed leaf nitrogen and carbon content and leaf volatiles to gauge differences between the leaflet types. In choice and no‐choice scenarios, larvae consume approximately the same amount of leaf area and display no preference between fertile and sterile leaflets. However, females deposited significantly more eggs on fertile than on sterile leaflets. Oviposition choice had no effect on larval development times, pupal weights, or successful eclosure. Nitrogen and carbon content did not differ between fertile and sterile samples, but sterile leaflets contain more 1‐octen‐3‐ol, which may act as an herbivory deterrent. The propagule attack imposed by N. conspurcatalis feeding on fertile leaflets is unlikely to provide adequate control, but could be beneficial as part of a suite of biological control agents and other control methods.

Potential Role of Masting by Introduced Bamboos in Deer Mice (Peromyscus maniculatus) Population Irruptions Holds Public Health Consequences

We hypothesized that the ongoing naturalization of frost/shade tolerant Asian bamboos in North America could cause environmental consequences involving introduced bamboos, native rodents and ultimately humans. More specifically, we asked whether the eventual masting by an abundant leptomorphic (“running”) bamboo within Pacific Northwest coniferous forests could produce a temporary surfeit of food capable of driving a population irruption of a common native seed predator, the deer mouse (Peromyscus maniculatus), a hantavirus carrier. Single-choice and cafeteria-style feeding trials were conducted for deer mice with seeds of two bamboo species (Bambusa distegia and Yushania brevipaniculata), wheat, Pinus ponderosa, and native mixed diets compared to rodent laboratory feed. Adult deer mice consumed bamboo seeds as readily as they consumed native seeds. In the cafeteria-style feeding trials, Y. brevipaniculata seeds were consumed at the same rate as native seeds but more frequently than wheat seeds or rodent laboratory feed. Females produced a median litter of 4 pups on a bamboo diet. Given the ability of deer mice to reproduce frequently whenever food is abundant, we employed our feeding trial results in a modified Rosenzweig-MacArthur consumer-resource model to project the population-level response of deer mice to a suddenly available/rapidly depleted supply of bamboo seeds. The simulations predict rodent population irruptions and declines similar to reported cycles involving Asian and South American rodents but unprecedented in deer mice. Following depletion of a mast seed supply, the incidence of Sin Nombre Virus (SNV) transmission to humans could subsequently rise with dispersal of the peridomestic deer mice into nearby human settlements seeking food.

Minimum threshold for establishment and dispersal of Lilioceris cheni (Coleoptera: Chrysomelidae): a biological control agent of Dioscorea bulbifera

ABSTRACT The successful establishment or failure of a new population is often attributed to propagule pressure, the combination of the number of independent introduction events, and the number of individuals released at each event. The design of optimal release strategies for biological control agents benefits from an understanding of the impact of propagule pressure on the species being released. The dispersal rate of individuals from nascent population foci can also affect establishment success. We assessed the minimum threshold for establishment and measured dispersal of Lilioceris cheni (Coleoptera: Chrysomelidae), a biological control agent for Dioscorea bulbifera (Dioscoreales), air potato. Replicated releases of 10, 50, and 100 adults of L. cheni were conducted on the east and west coasts of south Florida. Dispersal was measured from 19 of these sites plus 19 additional release locations in south and central Florida. Lilioceris cheni established populations from all three release sizes with no apparent influence of site location. Releases of 10, 50, and 100 adults resulted in 50%, 67%, and 85% establishment, respectively. Beetles dispersed an average of 1.41 ± 0.515 km/yr. Dispersal distance was significantly affected by the time since release but not the number of individuals released. Our results suggest that future releases of 100 individuals could be spaced several kilometres apart on the landscape to facilitate rapid colonisation of D. bulbifera infestations.